The invention is directed to a suction oil filter for transmissions or engines with a top shell 1, a bottom shell 2, with an oil suction opening 3 and an oil outlet 4, said suction oil filter being positioned in an oil pan or in the transmission housing.
Nowadays, suction oil filters are conventionally used in automatic transmissions to filter transmission oil. Suction oil filters are installed in transmissions in different ways. Usually the filters are screwed onto the control device situated above them or onto the transmission housing, and the filter is usually positioned on the underside of the transmission housing. There are also other uses in which the suction oil filter is integrated in the oil pan or within the transmission housing. To fasten the suction oil filter, the oil filter outlet is first inserted with the aid of a seal into a corresponding transmission opening and the oil pan or halves of the transmission are subsequently fitted. In these uses, the filter is held in its position solely by the oil pan or transmission halves and by its fastening and fixture at the oil outlet. In some cases springs are employed in the oil pan in order to keep the suction oil filter in a constant position in the transmission.
However, this set-up yields considerable disadvantages, particularly in the operation and fastening of the suction oil filter. Firstly, it is possible for the suction oil filter during operation to become displaced in its intake position owing to the given tolerances, thus resulting in changes in transmission oil flow. In particular, this can have an effect on the oil volume. The latter must be maintained in such a way that the intake position of the suction oil filter always remains completely below the oil surface level, whatever the vehicle position. Since the oil volume varies owing to the tolerances arising during fastening and owing to the possibility of displacement, a relatively large quantity of oil must be kept in circulation for functional reasons. This is costly and is a source of additional technical problems and costs on other functionally important transmission components.
Furthermore, more recent transmissions, e.g. CVT transmissions, which are hydraulically controlled with electronics or pressure-dependently, react very sensitively to pressure variations or to the incorrect intake of air which may arise during oil filtration with conventionally fastened suction oil filters as a result of displacements or tolerances. This may result in malfunctions of the hydraulic control of CVT transmissions or even in transmission failure due to disablement of the hydraulic control.
The technical object of the invention is therefore to provide a suction oil filter which is positioned in the oil pan or transmission in such a way that a defined distance is assured between the oil intake opening and the oil pan base or transmission housing so that the tolerances of the required oil flow can be reduced and so that uniform oil flow and trouble-free function are assured.
This technical object is achieved by a suction oil filter for transmissions or engines which has arranged in the intake opening 3 a movable intake tube 5 which is pressed by resilient means 6 mounted on the inside of the intake tube 5 outward onto the oil pan base 8, thus creating an oil intake opening at a defined constant distance from the oil pan base or transmission housing.
The suction oil filter can be positioned in an oil pan. However, it is also possible for the suction oil filter to be positioned in the transmission housing directly. In the latter case, no oil pan is necessary as the transmission housing performs the function of the oil pan.
In a preferred embodiment, the resilient means is a spring which presses onto the movable intake tube 5 and thus preloads the intake tube. In another preferred embodiment, the oil suction opening 3 is situated in the bottom shell 2 of the suction oil filter. In a preferred embodiment, the intake tube 5 has on its outside one or more spacers 7 which in a particularly preferred embodiment can be pin-shaped. When the suction oil filter is installed in the oil pan or in the transmission housing, the intake tube rests upright with this pin on the oil pan base or in the transmission housing, whereby the intake tube 5 is pressed by the spring against the base or the transmission housing. This creates a defined distance between the intake opening and the oil pan base or transmission housing which always remains constant while the vehicle is in motion and independently of the viscosity of the oil or any vibrations and driving situations.
In another preferred embodiment, the intake tube has on its inside another spring guide pin 9, on which one end of the spring 6 is mounted. The other end of the spring 6 is mounted in a preferred embodiment against the top shell of the suction oil filter or pin of the top shell.
The suction tube 5 also has sealing means 10 in order to ensure the sealing of the outer rim of the intake tube against the inner rim of the intake opening and in order that oil flow takes place exclusively through the intake tube. An O-ring is preferably employed as the sealing means.
Furthermore, the intake tube 5 has at its top end a continuous or discontinuous all-round swelling 11 so that the intake tube cannot slide down out of the intake opening. In its uninstalled state, the intake tube is pressed outward as far as it will go by the spring arranged in the suction oil filter until the all-round swelling comes to rest against the edge of the oil pan base. In its installed state, the intake tube 5 is pressed back into the housing of the suction oil filter partly by the oil pan base or transmission housing and then remains under tension in a defined position.
The suction oil filter is installed in the transmission in the conventional manner, said suction oil filter being initially inserted so that it rests against the control device or the transmission housing, and preferably against the underside of the transmission housing. Due to the subsequent mounting of the oil pan, the movable intake tube 5 is now preloaded further and pressed into a predefined position. By means of the preferably positioned spacers on the underside of the intake tube, a constant distance between the intake opening and the oil pan or transmission housing is set in a design-related fashion. Furthermore, the suction oil filter is fixed due to the design in the given transmission position. No other fastening elements are required.
The suction filter according to the invention has considerable advantages over the suction filters of the prior art. A defined, constant distance is created between the suction oil opening and the oil pan base or transmission housing. There is also a compensation of the tolerances of the transmission housing, oil pan, control device and suction oil filter. Furthermore, no further fastening of the suction oil filter is necessary, and the suction oil filter is thus very easy to install.